Genetic Algorithm to Optimize the Design of High Temperature Protective Clothing Based on BP Neural Network

For the clothing design for high-temperature operation, the theory or method such as partial differential, nonlinear programming and finite difference method was first applied to construct the overall heat transfer model of “high temperature environment--clothing--air layer--skin” and draw the temperature distribution map. Secondly, according to the human body burn model, the optimal parameters of fabric thickness are obtained preliminarily. Finally, the weights and thresholds of BP neural network were optimized by genetic algorithm, and these optimized values were assigned to the optimized BP neural network, and the nonlinear thickness function was approximated and optimized with MATLAB.

Laser-based Thickness Control in a Double-Side Polishing System for Silicon Wafers

Thickness control is a critical process of automated polishing of large and thin Si wafers in the semiconductor industry. In this paper, an elaborate double-side polishing (DSP) system is demonstrated, which has a polishing unit with feedback control of wafer thickness based on the scan data of a laser probe. Firstly, the mechanical structure, as well as the signal transmission and control of the DSP system, are discussed, in which the thickness feedback control is emphasized. Then, the precise positioning of the laser probe is explored to obtain the continuous and valid scan data of the wafer thickness. After that, a B-spline model is applied for the characterization of the wafer thickness function to provide the thickness control system with credible thickness deviation information. Finally, experiments of wafer-thickness evaluation and control are conducted on the presented DSP system. With the advisable number of control points in B-spline fitting, the thickness variation can be effectively controlled in wafer polishing with the DSP system, according to the experimental results of curve fitting and the statistical analysis of the experimental data.

Measurement of $$W^\pm $$ boson production in Pb+Pb collisions at $$\sqrt{s_{\mathrm{NN}}} = 5.02~\text {Te}\text {V}$$ with the ATLAS detector

A measurement of $$W^\pm $$W± boson production in Pb+Pb collisions at $$\sqrt{s_\mathrm {NN}} = 5.02~\text {Te}\text {V}$$sNN=5.02Te is reported using data recorded by the ATLAS experiment at the LHC in 2015, corresponding to a total integrated luminosity of $$0.49\;\mathrm {nb^{-1}}$$0.49nb-1. The $$W^\pm $$W± bosons are reconstructed in the electron or muon leptonic decay channels. Production yields of leptonically decaying $$W^\pm $$W± bosons, normalised by the total number of minimum-bias events and the nuclear thickness function, are measured within a fiducial region defined by the detector acceptance and the main kinematic requirements. These normalised yields are measured separately for $$W^+$$W+ and $$W^-$$W- bosons, and are presented as a function of the absolute value of pseudorapidity of the charged lepton and of the collision centrality. The lepton charge asymmetry is also measured as a function of the absolute value of lepton pseudorapidity. In addition, nuclear modification factors are calculated using the $$W^\pm $$W± boson production cross-sections measured in pp collisions. The results are compared with predictions based on next-to-leading-order calculations with CT14 parton distribution functions as well as with predictions obtained with the EPPS16 and nCTEQ15 nuclear parton distribution functions. No dependence of normalised production yields on centrality and a good agreement with predictions are observed for mid-central and central collisions. For peripheral collisions, the data agree with predictions within 1.7 (0.9) standard deviations for $$W^-$$W- ($$W^+$$W+) bosons.

Raman spectroscopic study of the influence of voltage-time on titania growth-fast anodized nanostructures

Many studies, focused in TiO2 nanotubes obtained by anodization, uses frequently a NH4F salt concentration from 0.3 – 0.5 wt% and the information about how voltage and time affects to nanotubes morphology, are valid for these concentration, moreover, this range induces a long time of anodized. TiO2 nanotubes were prepared by anodization process of a set of titanium foils in order to study the influence of time and voltage on the morphology of them. The anodization process consists of an organic media of ethylene glycol and 1.2 wt% of NH4F salts, voltage from 5 to 30 V for a time period from 1 to 6 hours, constant potential of 30 V for a time lapse from 10 to 360 minutes and 5 to 480 seconds. All anodized samples are rinsed and annealed to 400 °C by 3 hours to obtain an anatase crystalline structure. The morphological characterization was carried out by Field Emission Scanning Electron Microscopy (FESEM) to verify the presence of the nanostructures: nanopores, nanotubes and nanograss, these nanostructures were identified to appear for a time period from 5 to 480 seconds, 10 to 60 minutes and 1 to 6 hours, respectively. The surface morphology, inner diameter and length of the nanotubes varied with the electrochemical anodization parameters. Raman spectroscopy was used for optical characterization in order to identify the changes in signal intensity and Eg mode Shift and it was observed that intensity suffers an increment and Eg mode suffers a blue shift as a thickness function.

An Optimal Control Problem for A Viscoelastic Plate in a Dynamic Contact with an Obstacle

We deal with an optimal control problem governed by a nonlinear hyperbolic initial-boundary value problem describing the perpendicular vibrations of a simply supported anisotropic viscoelastic plate against a rigid obstacle. A variable thickness of a plate plays the role of a control variable. We verify the existence of an optimal thickness function.

Morphological and Raman Study of an Anodized Tio2 Nanotubular Matrix without Presence of Nanograss, Using Graphite as Cathode

One set of TiO2 nanotubes is anodized to identify and study the time lapse of a matrix of them without presence of nanograss as a residual layer. The anodization process consists of an organic media of ethylene glycol and NH4 F salts, constant voltage for a time period from 10 to 60 minutes. All anodized samples are rinsed and annealed to 400 °C by 2 hours to obtain an anatase crystalline structure. The morphological characterization was carried out by Field Emission Scanning Electron Microscopy to verify the presence of the nanotubes and calculate the surface roughness factor and film porosity. It was observed that roughness factor and porosity doesn’t have important variations, as time function, except for 60 minutes where nanograss has a strong presence and the gaps between nanotubes are minimal. Raman Spectroscopy was used for optical characterization in order to identify the changes in signal intensity and Eg mode Shift associated with anodization time. It was observed that intensity suffers an increment and Eg mode Shift suffers a decrement as thickness function (anodization time).

Stable finite volume element schemes for the shallow-ice approximation

ABSTRACTThe isothermal, non-sliding shallow-ice approximation, combined with mass conservation, is a fundamental model for ice-sheet and glacier flow. It determines the ice extent, geometry and velocity by the solution of a free-boundary problem. In this paper, the steady-state form of this problem is solved directly, without time-stepping, thereby demonstrating a fully implicit scheme with no stability restrictions. The classical Mahaffy (1976) finite difference method is first reinterpreted as a ‘finite volume element’ scheme that has both an everywhere-defined approximate thickness function and an approximation of the conservation equation in flux integral form. From this reinterpretation an improved scheme is built by using better quadrature in the integral and upwinding on that part of the flux which is proportional to the bed gradient. The discrete equations are then solved by a parallel Newton scheme which respects the constraint that ice thickness is non-negative. The results show good accuracy on both flat-bed and bedrock-step exact solutions. The method is then applied at high resolution to model the steady-state geometry of the Greenland ice sheet, using only bedrock elevation and present-day surface mass balance as input data.